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61. Topband: Folded wire verticals (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Tue, 16 Jan 2001 23:24:40 +0100; N4UH: Hi Henry, I think you're mixing up radiation resistance with feed point impedance. The Rr of the aerial is related with its electrical height and doesn't change if the radiator is series or shu; /archives//html/Topband/2001-01/msg00168.html (8,009 bytes)
62. Topband: RE: BOG antenna notes (score: 1): Author: i4jmy@iol.it (i4jmy@iol.it); Date: Fri, 19 Jan 2001 15:31:15 +0100; With all the respect, on top band a 260 ft is short and hasn't very much to do with Beverages in terms of pattern and performance. The F/B is not really a F/B but only a sort of null, moreover limite; /archives//html/Topband/2001-01/msg00192.html (7,211 bytes)
63. Topband: "T" or Inverted L? (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Mon, 22 Jan 2001 23:46:27 +0100; K8GG: The boom doesn't make the element thicker because it is not a part of the element being located below. The strap size is what changes the equivalent diameter of the antenna element but actually; /archives//html/Topband/2001-01/msg00228.html (8,438 bytes)
64. Topband: Loop-family antenna notes (score: 1): Author: i4jmy@iol.it (i4jmy@iol.it); Date: Fri, 1 Dec 2000 17:14:00 +0100; W8JI: Tom is right. Small vertical loops, infact, perfeclty couple with vertically polarized antennas in the nearby. It's a fact anyway, that medium size resonant small loops are far superior if comp; /archives//html/Topband/2000-12/msg00005.html (9,787 bytes)
65. Topband: Preamp update (score: 1): Author: i4jmy@iol.it (i4jmy@iol.it); Date: Wed, 6 Dec 2000 10:02:16 +0100; W7IUV: A loop with a resistive termination is inherently broadband. It has a very low efficiency on lower bands but its attenuation decreases in the higher part of RF spectrum. Delivering a lot of un; /archives//html/Topband/2000-12/msg00047.html (7,472 bytes)
66. Topband: Dual Band Inv L - 2 Points to clarify (score: 1): Author: i4jmy@iol.it (i4jmy@iol.it); Date: Tue, 19 Dec 2000 13:42:53 +0100; Hi Brian, if my memory doesn't fail, once I analyzed something very similar for a friend, the feed point impedance of your antenna should be in the range of 40 Ohm resistive on 80m (3.5 MHz) and 6 -j; /archives//html/Topband/2000-12/msg00109.html (8,173 bytes)
67. Topband: Shunt feed - how high is high enough? (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Wed, 27 Dec 2000 23:31:55 +0100; Hi Pete, I'd rather say how low is low enough.... When a tower is self resonant the current distribution is linear and a pure voltage shunt feed will drop into a folded unipole. When the radiator is; /archives//html/Topband/2000-12/msg00161.html (8,688 bytes)
68. Topband: High Z vs Low Z shunt feed tower (score: 1): Author: i4jmy@iol.it (i4jmy@iol.it); Date: Mon, 6 Nov 2000 10:18:00 +0100; If the tower were self resonant, the current distribution would be linear and a voltage shunt feed will be just a folded unipole. When the radiator is not resonant, but loaded, the current distributi; /archives//html/Topband/2000-11/msg00036.html (8,895 bytes)
69. Topband: High Z vs Low Z shunt feed tower (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Mon, 6 Nov 2000 22:31:04 +0100; In any case, a tower needs to be shorter than electrical quarter wavelength, or anyway Z=R-Jx , to be suitable for canonical gamma or omega matching. Concerning tap point impedance, calculations are; /archives//html/Topband/2000-11/msg00041.html (8,777 bytes)
70. Topband: Balanced Line Radiation (score: 1): Author: i4jmy@iol.it (i4jmy@iol.it); Date: Tue, 14 Nov 2000 15:52:25 +0100; The unbalance of a balanced line connected to a balanced load (dipole) is generally small, expecially if the line runs free and vertically. If the spacing between conductors is not comparable with WL; /archives//html/Topband/2000-11/msg00073.html (7,200 bytes)
71. Topband: Beverage height experiment results (score: 1): Author: i4jmy@iol.it (i4jmy@iol.it); Date: Thu, 23 Nov 2000 10:57:41 +0100; On weak signals, the antenna efficiency still plays a role and it has to be found, of course when it's possible, an optimal compromise between directivity and available signals at antenna terminals.; /archives//html/Topband/2000-11/msg00143.html (9,744 bytes)
72. Topband: Beverage Front to Back Non-exsistant (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Sun, 15 Oct 2000 12:00:02 +0200; Isn't your beverage coupled to some vertical radiator (i.e. a tower) in the nearby ? Isn't it that the matching transformer is an autotransformer (or defective) and coaxial acts like a snake antenna; /archives//html/Topband/2000-10/msg00089.html (7,796 bytes)
73. Topband: Beverage Front to Back Non-exsistant (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Sun, 15 Oct 2000 17:22:56 +0200; In case of coupling, the distance between a vertical and a beverage is what matters. Unless the inv L is half wave resonant (what's not raccomandable), to let the inv L floating (disconnect from coax; /archives//html/Topband/2000-10/msg00091.html (7,525 bytes)
74. Topband: More 160M Receivers-Mid $$ (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Fri, 1 Sep 2000 19:48:55 +0200; You can buy a lot of better equipments at low/er price in a second hand market. The choice is wide and nothing substantially changed in last 20 years to push in favour of new transceivers belonging t; /archives//html/Topband/2000-09/msg00007.html (6,898 bytes)
75. Topband: shunt-fed bandwidth (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Thu, 7 Sep 2000 19:39:45 +0200; In my tests I found an RF ammeter (thermocouple) to measure the whole radials current matches fine with the fields results. More or less, when current does not continue to increase noticeably, also f; /archives//html/Topband/2000-09/msg00027.html (7,177 bytes)
76. Topband: Hybrid Coupler (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Sat, 9 Sep 2000 16:15:28 +0200; In a four ports hybrid coupler the rate and phase between the output and coupled port is fixed. The fourth terminated port serves to absorb the energy that's not dissipated, or by the main output loa; /archives//html/Topband/2000-09/msg00040.html (8,078 bytes)
77. Topband: Hybrid Coupler (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Sat, 9 Sep 2000 17:22:08 +0200; I'm generally speaking with no references to ON4UN book or his specific project. The hybrid couplers I know (and the magic Tee derivations) are broadband directional couplers where phase between port; /archives//html/Topband/2000-09/msg00042.html (7,641 bytes)
78. Topband: Re: [TowerTalk] Winding Beverage RX Balun de K0FF (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Sat, 16 Sep 2000 20:27:27 +0200; After some bad experiences, to prevent damages from (indirect) lightning strikes I stopped with using small cores and thin wires turning in favour of medium-large toroidal ferrite cores (AL = 4000, o; /archives//html/Topband/2000-09/msg00077.html (8,608 bytes)
79. Topband: 40 foot diameter shielded loop (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Wed, 20 Sep 2000 23:49:50 +0200; A 40 ft loop (shielded or not) is too big, likewise the capacitance due to RG213. Try with much smaller diameters and possibly using cables with less capacitance per meter. A magnetical loop whose ci; /archives//html/Topband/2000-09/msg00112.html (7,135 bytes)
80. Topband: 2 wire beverage (score: 1): Author: i4jmy@iol.it (Maurizio Panicara); Date: Fri, 22 Sep 2000 09:49:11 +0200; Leaving one wire open and grounding the other you typically achieve 12 dB F/B that's finally not bad; the primary windings of transformers at RX side need always to be alternatively terminated when n; /archives//html/Topband/2000-09/msg00124.html (7,688 bytes)

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